Natural gas is predominantly transported and handled by pipeline as a gaseous medium or in the form of Liquid Natural Gas (LNG) in ships or peak shaving facilities. Many gas reserves are remotely located with respect to markets, and of a size smaller than the levels of recoverable product deemed economically worthwhile moving to market by pipeline or Liquefied Natural Gas (LNG) ships.
The slow commercialization of Compressed Natural Gas (CNG) shipping offering volumetric containment of natural gas up to half of the 600 to 1 ratio offered by LNG has shown the need for a method which is complimentary to both these aforementioned systems. The method described herein is intended to fulfill the existing need between these two systems.
The energy intensity of LNG systems typically requires 10 to 14% of the energy content of produced gas by the time the product is delivered to market hubs. CNG has even higher energy requirements associated with gas conditioning, heat of compression of the gas, its cooling and subsequent evacuation from transport containers. As outlined in U.S. patent application Ser. No. 10/928,757 (“the '757 application), filed Aug. 26, 2004, which is incorporated by reference, the handling of natural gas in a liquefied matrix as a liquid medium (referred to as Compressed Gas Liquid™ (CGL™) gas mixture) without resorting to cryogenic conditions has its advantages in this niche market. Both in the compression of gas to a liquid phase for storage conditions, and in the 100% displacement of CGL™ gas mixture during offloading from transportation systems, there are distinct energy demand advantages in the CGL™ process.
The CGL™ process energy demand to meet storage conditions of 1400 psig at −40° F. is a moderate requirement. The higher pressures necessary for effective values of CNG (1800 psig to 3600 psig) at 60° F. down to −20° F., and the substantially lower cryogenic temperatures for LNG (−260° F.) give rise to the greater energy demands for the CNG and LNG processes.
Thus it is desirable to provide systems and methods that facilitate the storage and transport of natural or produced gas with lower energy demands.